1 - User completes form on the index.html page
2 - Submits the form (an email form)
3 - A new tab is opened to display the email success page, the old tab still has values
4 - User clicks the OK button on the emailsuccess.htm It opens a new index.html page. Now I have two index.html.

What is the standard practice for implementing this? A pop-up window for the email confirmation?